U.S. patent number 4,886,242 [Application Number 07/250,772] was granted by the patent office on 1989-12-12 for pneumatic hydraulic side lifting jack.
This patent grant is currently assigned to Hein-Werner Corporation. Invention is credited to Leonard Eck, Reinald D. Liegel, Charles Naber, Garry J. Sabel.
United States Patent |
4,886,242 |
Eck , et al. |
December 12, 1989 |
Pneumatic hydraulic side lifting jack
Abstract
A side lifting jack having a pneumatically and hydraulically
actuated lifting cylinder for raising a lift arm of the side
lifting jack. The jack includes a hydraulic fluid reservoir and air
pressure is supplied to the hydraulic fluid reservoir to cause
hydraulic fluid to be delivered to the lift cylinder. A flow
restricting device controls the rate of flow of hydraulic fluid
into or out of the hydraulic cylinder and prevents sudden movement
of the jack or sudden extension of the lift cylinder assembly in
the event that the load on the lift jack is suddenly reduced or
removed from the lift jack. The jack also includes a ratch and pawl
arrangement to selectively prevent retraction of the piston of the
hydraulic cylinder and lowering of the jack.
Inventors: |
Eck; Leonard (McPherson,
KS), Liegel; Reinald D. (Waukesha, WI), Naber;
Charles (Waukesha, WI), Sabel; Garry J. (South
Milwaukee, WI) |
Assignee: |
Hein-Werner Corporation
(Waukesha, WI)
|
Family
ID: |
22949079 |
Appl.
No.: |
07/250,772 |
Filed: |
September 28, 1988 |
Current U.S.
Class: |
254/8B |
Current CPC
Class: |
B66F
5/04 (20130101) |
Current International
Class: |
B66F
5/04 (20060101); B66F 5/00 (20060101); B66F
003/00 () |
Field of
Search: |
;254/3R,3B,3C,8R,8B,8C,2R,2B,1C,133,134,124,126 ;414/678 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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143755 |
|
Oct 1951 |
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AU |
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1556608 |
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Nov 1979 |
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DK |
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405664 |
|
Jul 1966 |
|
SE |
|
753786 |
|
Aug 1980 |
|
SU |
|
Primary Examiner: Watson; Robert C.
Attorney, Agent or Firm: Michael, Best & Friedrich
Claims
We claim:
1. A side lifting jack for lifting a vehicle, the side lifting jack
comprising:
a lift arm having opposite ends, one end of the lift arm being
supported by at least one wheel, and the one end of the lift arm
being adapted to extend under a vehicle,
jack means for supporting the other end of the lift arm, the jack
means including a hydraulic cylinder assembly including a hydraulic
cylinder and an extensible piston housed in the hydraulic cylinder,
the hydraulic cylinder assembly being generally vertically
extensible, one of the cylinder and the piston being connected by a
pivotal connection to the other end of the lift arm for raising the
other end of the lift arm in response to extension of the hydraulic
cylinder, and the other of the piston and cylinder including a
lower end, and an elongated brace member having opposite ends, one
of the opposite ends of the elongated brace being connected to said
lower end of the other of the piston and cylinder, and the other of
the opposite ends of the brace member being connected to the lift
arm in spaced relation from the other end of the lift arm.
2. A side lifting jack as set forth in claim 1 wherein the lift arm
includes a hydraulic fluid reservoir, and further including means
for connecting a source of air pressure to the hydraulic fluid
reservoir.
3. A side lifting jack as set forth in claim 2 and further
including means for connecting the hydraulic fluid reservoir in the
lift arm to the hydraulic cylinder whereby hydraulic fluid can be
supplied from the fluid reservoir to the hydraulic cylinder when
air pressure is applied to the hydraulic fluid reservoir.
4. A side lifting jack as set forth in claim 1 and further
including means for selectively locking the piston in the selected
extended position, the means for selectively locking including a
plurality of stop members fixed to the piston and spaced apart
along the length of the piston, and a pawl supported by the
cylinder and selectively engageable with a selected one of the stop
members.
5. A side lifting jack as set forth in claim 4 wherein the pawl is
supported for movement between an engaging position wherein the
pawl prevents retraction of the piston into the cylinder and a pawl
retracted position wherein the pawl is spaced from the stop members
and the piston is freely movable with respect to the cylinder.
6. A side lifting jack as set forth in claim 1 wherein the
hydraulic cylinder has upper and lower ends, and wherein the
hydraulic cylinder is supported by the piston for vertical movement
in response to extension of the piston, the other end of the lift
arm being pivotally connected to the lower end of the cylinder.
7. A side lifting jack as set forth in claim 1 and further
including an elongated base having opposite ends, the elongated
base extending generally transversely to the axis of the lift arm,
wheels supporting opposite ends of the base, and the piston being
connected to the base intermediate its opposite ends, one end of
the elongated brace member being connected to one end of the lift
arm and an opposite end connected to one of the opposite ends of
the elongated base.
8. A side lifting jack as set forth in claim 1 and further
including means for restricting flow of hydraulic fluid into the
hydraulic cylinder, the means for restricting the flow including a
flow restricting orifice adapted to limit the rate of flow of
hydraulic fluid from the hydraulic fluid reservoir into the
hydraulic cylinder.
9. A side lifting jack for lifting a vehicle, the side lifting jack
comprising:
a lift arm having opposite ends, one end of the lift arm being
supported by at least one wheel and the one end of the lift arm
being adapted to extend under a vehicle,
jack means for supporting the other end of the lift arm, the jack
means including a cylinder assembly including a cylinder and an
extensible piston housed in the cylinder, the cylinder assembly
being generally vertically extensible, and one of the cylinder and
the piston being pivotally connected to the other end of the lift
arm for raising the other end of the lift arm in response to
extension of the cylinder, and
means for selectively locking the piston in the selected extended
position, the means for selectively locking including a plurality
of stop members fixed to the piston and spaced apart along the
length of the piston, and a pawl supported by the cylinder and
selectively engageable with a selected one of the stop members.
10. A side lifting jack as set forth in claim 9 wherein the pawl is
supported for movement between an engaging position wherein the
pawl prevents retraction of the piston into the cylinder and a pawl
retracted position wherein the pawl is spaced from the stop members
and the piston is freely movable with respect to the cylinder.
11. A side lifting jack as set forth in claim 9 wherein the
hydraulic cylinder has upper and lower ends, and wherein the
cylinder is supported by the piston for vertical movement in
response to extension of the piston, and further including means
for pivotally joining the other end of the lift arm to the lower
end of the cylinder.
12. A side lifting jack as set forth in claim 9 and further
including an elongated base having opposite ends, the elongated
base extending generally transversely to the axis of the lift arm,
wheels supporting opposite ends of the base, and the piston being
connected to the base intermediate its opposite ends, brace means
having opposite ends, one end connected to one end of the lift arm
and an opposite end connected to one of the opposite ends of the
elongated base.
13. A side lifting jack for lifting a vehicle, the side lifting
jack comprising:
a lift arm having opposite ends, one end of the lift arm being
supported by at least one wheel, and the one end of the lift arm
being adapted to extend under a vehicle, and the lift arm including
a hydraulic fluid reservoir,
jack means for supporting the other end of the lift arm, the jack
means including a hydraulic cylinder assembly including a hydraulic
cylinder and an extensible piston housed in the hydraulic cylinder,
the hydraulic cylinder assembly being generally vertically
extensible, and one of the cylinder and the piston being connected
to the other end of the lift arm for raising the other end of the
lift arm and in response to extension of the hydraulic cylinder,
and means for connecting a source of air pressure to the hydraulic
fluid reservoir.
14. A side lifting jack as set forth in claim 13 and further
including means for connecting the hydraulic fluid reservoir in the
lift arm to the hydraulic cylinder whereby hydraulic fluid can be
supplied from the fluid reservoir to the hydraulic cylinder when
air pressure is applied to the hydraulic fluid reservoir.
15. A side lifting jack as set forth in claim 13 and further
including means for selectively locking the piston in the selected
extended position, the means for selectively locking including a
plurality of stop members fixed to the piston and spaced apart
along the length of the piston, and a pawl supported by the
cylinder and selectively engageable with a selected one of the stop
members.
16. A side lifting jack as set forth in claim 15 wherein the pawl
is supported for movement between an engaging position wherein the
pawl prevents retraction of the piston into the cylinder and a pawl
retracted position wherein the pawl is spaced from the stop members
and the piston is freely movable with respect to the cylinder.
17. A side lifting jack as set forth in claim 15 wherein the
hydraulic cylinder is pivotally connected to the lift arm for
lifting the lift arm in response to extension of the piston.
18. A side lifting jack as set forth in claim 13 wherein the
hydraulic cylinder has upper and lower ends, and wherein the
hydraulic cylinder is supported by the piston for vertical movement
in response to extension of the piston, and further including means
for pivotally joining the other end of the lift arm to the lower
end of the cylinder.
19. A side lifting jack as set forth in claim 13 and further
including an elongated base having opposite ends, the elongated
base extending generally transversely to the axis of the lift arm,
wheels supporting opposite ends of the base, and the piston being
connected to the base intermediate its opposite ends, brace means
having opposite ends, one end connected to one end of the lift arm
and an opposite end connected to one of the opposite ends of the
elongated base.
20. A side lifting jack as set forth in claim 13 and further
including means for restricting flow of hydraulic fluid into the
hydraulic cylinder, the means for restricting the flow including a
flow restricting orifice adapted to limit the rate of flow of
hydraulic fluid from the hydraulic fluid reservoir into the
hydraulic cylinder.
21. A side lifting jack for lifting a vehicle, the side lifting
jack comprising:
a lift arm having opposite ends, one end of the lift arm being
supported by at least one wheel, and the one end of the lift arm
being adapted to extend under a vehicle,
jack means for supporting the other end of the lift arm, the jack
means including a hydraulic cylinder assembly including a hydraulic
cylinder and an extensible piston housed in the hydraulic cylinder,
the hydraulic cylinder assembly being generally vertically
extensible, and one of the cylinder and the piston being connected
to the other end of the lift arm for raising the other end of the
lift arm in response to extension of the hydraulic cylinder, and an
elongated base having opposite ends, the elongated base extending
generally transversely to the axis of the lift arm, wheels
supporting opposite ends of the elongated base, and the piston
being connected to the elongated base intermediate its opposite
ends, brace means having opposite ends, one end connected to one of
the opposite ends of the elongated base.
22. A side lifting jack as set forth in claim 21 wherein the lift
arm includes a hydraulic fluid reservoir, and further including
means for connecting a source of air pressure to the hydraulic
fluid reservoir.
23. A side lifting jack as set forth in claim 21 and further
including means for connecting the hydraulic fluid reservoir in the
lift arm to the hydraulic cylinder whereby hydraulic fluid can be
supplied from the fluid reservoir to the hydraulic cylinder when
air pressure is applied to the hydraulic fluid reservoir.
24. A side lifting jack as set forth in claim 21 and further
including means for selectively locking the piston in the selected
extended position, the means for selectively locking including a
plurality of stop members fixed to the piston and spaced apart
along the length of the piston, and a pawl supported by the
cylinder and selectively engageable with a selected one of the stop
members.
25. A side lifting jack as set forth in claim 24 wherein the pawl
is supported for movement between an engaging position wherein the
pawl prevents retraction of the piston into the cylinder and a pawl
retracted position wherein the pawl is spaced from the stop members
and the piston is freely movable with respect to the cylinder.
26. A side lifting jack as set forth in claim 24 wherein the
hydraulic cylinder is pivotally connected to th e lift arm for
lifting the lift arm in response to extension of the piston.
27. A side lifting jack as set forth in claim 21 wherein the
hydraulic cylinder has upper and lower ends, and wherein the
hydraulic cylinder is supported by the piston for vertical movement
in response to extension of the piston, and further including means
for pivotally joining the other end of the lift arm to the lower
end of the cylinder.
28. A side lifting jack as set forth in claim 21 and further
including means for restricting flow of hydraulic fluid into the
hydraulic cylinder, the means for restricting the flow including a
flow restricting orifice adapted to limit the rate of flow of
hydraulic fluid from the cylinder fluid reservoir into the
hydraulic cylinder.
29. A side lifting jack for lifting a vehicle, the side lifting
jack comprising:
a lift arm having opposite ends, one end of the lift arm being
supported by at least o ne wheel and the one end of the lift arm
being adapted to extend under a vehicle.
jack means for supporting the other end of the lift arm, the jack
means including a cylinder assembly including a cylinder and an
extensible piston housed in the cylinder, the cylinder assembly
being generally vertically extensible, and one of the cylinder and
the piston being connected to the other end of the lift arm for
raising the other end of the lift arm in response to e extension of
the cylinder.
means for selectively locking the piston in the selected extended
position, the means for selectively locking including a plurality
of stop members fixed to the piston and spaced apart along the
length of the piston, and a pawl supported by the cylinder and
selectively engageable with a selected one of the stop members, and
an elongated base having opposite ends, the elongated base
extending generally transversely to the axis of the lift arm,
wheels supporting opposite ends of the base, and the piston being
connected to the base intermediate its opposite ends, brace means
having opposite ends, one end connected to one end of the lift arm
and an opposite end connected to one of the opposite ends of the
elongated base.
30. A side lifting jack as set forth in claim 29 wherein the pawl
is supported for movement between an engaging position wherein the
pawl prevents retraction of the piston into the cylinder and a pawl
retracted position wherein the pawl is spaced from the stop members
and the piston is freely movable with respect to the cylinder.
31. A side lifting jack as set forth in claim 29 wherein the
hydraulic cylinder has upper and lower ends, and wherein the
cylinder is supported by the piston for vertical movement in
response to extension of the piston, and further including means
for pivotally joining the other end of the lift arm to the lower
end of the cylinder.
Description
FIELD OF THE INVENTION
The invention relates to vehicle jacks and vehicle repair
equipment, and more particularly to jack assemblies used in raising
one side of a vehicle.
BACKGROUND PRIOR ART
An example of a prior art side lifting jack is illustrated in the
Gray et al. U.S. Pat. No. 4,379,545, issued Apr. 12, 1983.
Attention is also directed to the Nielsen U.S. Pat. No. 3,252,590,
issued May 24, 1966; the Gray U.S. Pat. No. 3,302,927, issued Feb.
7, 1967 and Australian Patent Specification No. 143,755.
Attention is also directed to British Patent No. 1 556 608; Russian
Publication No. 753785; Russian Publication No. 753786; the Wooding
U.S. Pat. No. 4,127,255, issued Nov. 28, 1978; and the Feilbach et
al. U.S. Pat. No. 3,268,208, issued Aug. 23, 1966. Attention is
further directed to the Arnes U.S. Pat. No. 3,014,698, issued Dec.
26, 1961; the Trautman et al. U.S. Pat. No. 2,730,903, issued Jan.
17, 1956; the Forster U.S. Pat. No. 2,588,509, issued Mar. 11,
1952: the Mandelko et al. U.S. Pat. No. 2,494,099, issued Jan. 10,
1950; the Johnson U.S. Pat. No. 2,400,235, issued May 14, 1946; the
Bentley U.S. Pat. No. 867,549, issued Oct. 1, 1907; the Stark U.S.
Pat. No. 815,757, issued Mar. 20, 1906; Swiss Patent No. 405 664;
and the Jackson U.S. Pat. No. 2,404,577, issued July 23, 1946.
SUMMARY OF THE INVENTION
The present invention provides an improved side lifting jack having
a pneumatically and hydraulically actuated lifting cylinder for
raising a lift arm of the side lifting jack. The jack includes a
hydraulic fluid reservoir and means for supplying air pressure to
the hydraulic fluid reservoir to cause hydraulic fluid to be
delivered to the lift cylinder. The lifting jack further includes a
flow restricting device to control flow of hydraulic fluid into or
out of the hydraulic cylinder and thereby prevent sudden movement
of the jack or sudden extension of the lift cylinder assembly in
the event that the load on the lift jack is suddenly reduced or
removed from the lift jack. The jack further includes a ratch and
pawl arrangement to selectively prevent retraction of the piston of
the hydraulic cylinder and lowering of the vehicle in the event of
failure of the hydraulic cylinder.
More particularly, the invention includes a side lifting jack for
lifting a vehicle and including a lift arm having one end supported
by at least one wheel and the other end adapted to extend under a
vehicle, and jack means for supporting the other end of the lift
arm, the jack means including a hydraulic cylinder and an
extensible piston housed in the hydraulic cylinder, and one of the
cylinder and the piston being connected to the other end of the
lift arm for raising the other end of the lift arm in response to
extension of the hydraulic cylinder. In one embodiment of the
invention the lift arm includes a hydraulic fluid reservoir, and
means are also provided for connecting a source of air pressure to
the hydraulic fluid reservoir. Means are also provided for
connecting the hydraulic fluid reservoir in the lift arm to the
hydraulic cylinder such that hydraulic fluid can be supplied from
the fluid reservoir to the hydraulic cylinder when air pressure is
applied to the hydraulic fluid reservoir.
In a preferred embodiment of the invention means are further
provided for selectively locking the piston in a selected extended
position, this locking means including a plurality of stop members
fixed to the piston and spaced apart along the length of the
piston, and a pawl supported by the cylinder and selectively
engageable with a selected one of the stop members, the pawl being
supported for movement between an engaging position wherein the
pawl prevents retraction of the piston into the cylinder and a pawl
retracted position wherein the pawl is spaced from the stop
members, and the piston is freely movable with respect to the
cylinder.
In one embodiment of the invention the hydraulic cylinder is
supported by the piston for vertical movement in response to
extension of the piston, and means are further provided for
pivotally joining the other end of the lift arm to the lower end of
the cylinder to permit relative pivotal movement of the cylinder
with respect to the lift arm as the cylinder extends and retracts.
This relative pivotal movement eliminates side loading on the
components of the lifting jack and also permits the lifting jack
components to follow the arc of the side of the vehicle during the
lifting and retracting operations.
Various other features and advantages of the invention will be
apparent by reference to the following description of a preferred
embodiment, from the drawings and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation view of a side lift jack embodying the
invention and with portions broken away.
FIG. 2 is an elevation view of the side lift jack illustrated in
FIG. 1.
FIG. 3 is a view similar to FIG. 1 and showing the side lift jack
in elevated condition.
FIG. 4 is an enlarged partial end elevation view of the lift jack
illustrated in FIGS. 1 through 3.
FIG. 5 is an enlarged partial view of a portion of the side lift
jack illustrated in FIG. 1.
FIG. 6 is a schematic view of the hydraulic and pneumatic circuit
of the side lift jack shown in FIGS. 1-5.
Before describing a preferred embodiment of the invention in
detail, it is to be understood that the invention is not limited to
the details of construction and to the arrangement of the
components set forth in the following description or illustrated in
the drawings. The invention is capable of other embodiments and of
being practiced and carried out in various ways. Also, it is to be
understood that the phraseology and terminology employed herein is
for the purpose of description and should not be regarded as
limiting.
DESCRIPTION OF A PREFERRED EMBODIMENT
Illustrated in FIG. 1 is a side lifting jack 10 embodying the
invention and for use in lifting one side of a vehicle (not shown)
to permit repair or maintenance work on the vehicle. The side
lifting jack includes a lift arm 12 having opposite ends, one end
14 being supported by a caster or wheel 16 and adapted to extend
under a vehicle. In a preferred form of the invention, the lift arm
12 will have a length of at least approximately two-thirds the
width of the vehicle to be lifted. The opposite end of the lift arm
12 includes a transversely extending vehicle support member 19
adapted to be positioned beneath a side of a vehicle or beneath a
side portion of a vehicle frame to engage the vehicle and for
lifting the side of the vehicle. The vehicle support member 19 is
supported by a pair of parallel, spaced apart, generally vertical
plates 21 projecting upwardly from the end of the lift arm and
fixed to the lift arm. While the saddle 19 could have other
construction in the specific arrangement illustrated in the
drawings, the saddle 19 has a configuration adapted to house and
retain the pinch weld of an automobile.
The opposite end of the lift arm 12 is supported by a piston and
cylinder assembly 18 including a generally vertically oriented
cylinder 20 and piston 22 having a downwardly extending piston rod
24. In the illustrated arrangement, the hydraulic cylinder 20 is
supported by the downwardly extending piston 22 for generally
vertical movement, and the cylinder 20 includes a lower end
pivotally joined to the opposite end 26 of the lift arm 12. More
particularly, a bracket 28 is fixed to the lower end of the
cylinder 20, and the vertical plates 21 fixed to the end 26 of the
lift arm 12 are connected to the bracket 28 by a hinge pin or
connecting pin 30.
The side lifting jack 10 also includes a base 32 which in the
particular arrangement illustrated in the drawings is comprised of
an elongated bar or angle having opposite ends supported by spaced
apart casters 34.
The piston rod 24 of the piston and cylinder assembly 18 includes a
lower end 36 fixed to the bar 32 intermediate its opposite ends and
such that the lower end 36 of the piston rod 24 is supported by the
bar 32.
In a preferred form of the invention the lift arm 12 comprises an
elongated tank defining a hydraulic fluid reservoir 40 of
sufficient volume that the tank can house sufficient hydraulic
fluid to be supplied to the hydraulic cylinder 20. In a preferred
form of the invention the fluid reservoir 40 is operably connected
to the upper end of the hydraulic cylinder through hydraulic fluid
line 42. Fluid line 42 comprises a supply line for delivering
hydraulic fluid from the reservoir 40 to a chamber 46 defined by
the upper end of the cylinder 20. Means are also provided for
supplying air under pressure to the hydraulic fluid reservoir 40.
In the illustrated arrangement this means for supplying air to the
hydraulic fluid reservoir includes a coupling 48 and an air hose 44
extending from the coupling 48 to the hydraulic fluid reservoir. In
one form of the invention the coupling 48 can comprise a
conventional quick disconnect coupling for an air hose of the type
commonly included in auto repair facilities and service areas.
In a preferred form of the invention, the hydraulic fluid used in
the side lifting jack of the invention will be synthetic hydraulic
fluid or oil which will not mix with air in the system. One
hydraulic fluid which can be used is synthetic hydraulic fluid
manufactured by Ams/Oil, Inc., Superior, Wisconsin.
As illustrated in FIG. 1, means are further provided for
restricting the rate of flow of hydraulic fluid between the
reservoir 40 and the hydraulic cylinder 20. While in other
embodiments, other flow restricting means could be provided, in the
illustrated arrangement the flow restricting means comprises and
elongated tube 41 having a small diameter interior bore, the
elongated tube being housed in the reservoir and having an open end
43. In the illustrated arrangement the tube has a length of
approximately 58 inches and an internal bore diameter of 0.493
inches. This arrangement is effective to limit the flow of
hydraulic fluid through the fluid line 42 and thereby limits the
rate of flow of hydraulic fluid from the reservoir 40 to the
cylinder 20 and thereby controlling the rate of vertical lift of
the cylinder 20.
Also included is a manually operable control valve 52 for
controlling the air pressure supplied by line 44 to the hydraulic
fluid reservoir to provide for raising and lowering of the side
lifting jack. In the illustrated arrangement, the manually operable
valve 52 is controlled by a control lever 54. The control lever 54
and valve 52 are operable to permit the operator to increase the
air pressure in the hydraulic fluid reservoir 40 thereby forcing
hydraulic fluid into the cylinder to raise cylinder 20 or venting
air pressure from the reservoir 40 permitting flow of hydraulic
fluid out of the cylinder to the reservoir and lowering of the lift
jack.
Means are also provided for selectively mechanically supporting the
cylinder 20 in a raised position, this means including a plurality
of mechanical stops 80 fixed to the piston rod 24 and spaced along
its length. A pawl 82 is supported by the lower end of the cylinder
20 and selectively engages a selected one of the stops 80 when the
piston 22 is extended and the cylinder 20 is raised. The pawl 82 is
supported by a pivot pin 84 and pivots between a disengaged
position and a stop or engaging position. A handle 86 is connected
to the pawl by a connecting rod 88 and a bracket 90. In the
illustrated arrangement the pawl 82 is mounted eccentrically with
respect to the pivot pin 84, and the weight of the pawl 82, the
connecting rod 88 and handle 86 tend to bias the pawl toward a stop
engaging position.
During operation of the lift jack 10, the pawl 82 and stop members
80 selectively prevent downward movement of the cylinder 20 and
lift arm 12. Lowering of the lift jack requires the operator to
grip the handle 86 to disengage the pawl 82 and also actuate the
valve 52 to first raise the cylinder slightly to permit
disengagement with the pawl with the stop member and then actuation
of the valve to lower the lift arm.
The side lifting jack also includes a pair of elongated braces 100,
each of the braces 100 having one end pivotally connected to the
inwardly extending end 14 of the lift arm 12 and an opposite end
pivotally connected to an end of the base member 32 to provide
support between the inwardly extending end 14 of the lift arm 12
and the ends of the base 32.
Various features of the invention are set forth in the following
claims.
* * * * *